1. The Field of the Invention
The present invention generally relates to vascular entry devices. More particularly, the invention relates to blood containment devices for use with a vascular entry needle to provide visual and tactile confirmation that the needle tip has entered into a blood vessel and to allow for the introduction of an elongated medical instrument through the device.
2. The Relevant Technology
It is a common medical procedure to insert a hollow needle into a patient's blood vessel for the purpose of either withdrawing blood or introducing a drug, guide wire, guide catheter, or the like into the blood vessel. One difficulty with such procedures, however, is determining when the tip of the needle is properly placed within the selected blood vessel. Another concern is that unless the blood is contained, vascular pressure, and arterial pressure in particular, can force a leakage or spray of blood through the needle which will escape through the opposite end of the needle. This can create a risk to medical personnel of exposure to blood-borne viruses, such as hepatitis and HIV, that may be present in the patient's blood.
The problems of blood containment and confirming proper needle placement are particularly applicable during the procedure for introducing a guide wire, catheter, or the like, into a patient's artery for carrying out procedures in or around the patient's heart. Such catheterization involves first creating access to the selected artery using a vascular entry needle of sufficient bore, and then inserting a guide wire, guide catheter, or other catheter apparatus through the needle and into the selected artery. Often, the guide wire is first inserted and located in a desired position, after which the catheter is inserted over the guide wire to the desired position. Self-guiding catheters may also be inserted without first using a guide wire. After the catheter apparatus has been placed into the desired position, the vascular entry needle can then be removed by sliding it backwards over and off the proximal end of the guide wire apparatus.
In performing a catheterization procedure, as noted above, it is crucial that the vascular entry needle be properly positioned within the selected blood vessel. When an ordinary entry needle is used, entry of the needle tip into the blood vessel is indicated by the escape of blood at the proximal end of the needle. However, this has the attendant contamination problems mentioned above.
Another problem is that, during positioning, the needle can be accidentally pulled out of the blood vessel or pushed through the opposite side of the vessel wall, which defeats the catheterization procedure. Accordingly, it is important after the needle tip first enters the blood vessel to confirm that the tip remains properly positioned within the blood vessel.
Various blood containment devices exist which are directed to solving the above problems. Two such devices are the AngioDynamics.TM. SOS Bloodless.TM. Entry Needle (U.S. Pat. No. 5,122,121) and the Arrow-Fischell EVAN.TM. Vascular Entry Needle. Both of these devices have a vascular entry needle attached to a transparent plastic containment member. The plastic containment member has a catheter guideway extending therethrough which allows insertion of catheterization apparatus through the device. The catheter guideway has a barrier within it which blocks blood from escaping, but allows passage of the catheterization apparatus.
Both devices also have features for indicating when the needle tip enters a blood vessel. The AngioDynamics.TM. SOS Bloodless.TM. Entry Needle has a length of transparent, flexible plastic tubing which branches off from the plastic containment member and leads to a small, collapsed, transparent plastic blood bag. When the needle tip is inserted into an artery, blood travels through the needle, into the guideway of the plastic containment member, out through the plastic tubing, and into the small blood bag. The soft plastic tubing of this device purportedly permits palpitation and visualization of the arterial pulse. However, the attached tube and blood bag can be cumbersome, particularly once the blood bag is filled. Also, once the blood bag is filled, the visual confirmation of needle tip placement stops.
The Arrow-Fischell EVAN.TM. Vascular Entry Needle provides for visualization of blood in a different way. The lower portion of the catheter guideway is narrow (about equal to the needle bore) for approximately two inches. It then opens into an air chamber near the upper portion of the device. When the tip of the vascular entry needle enters an artery, blood travels under pressure through the needle and partially fills the narrow lower portion of the guideway. It does this by slightly compressing the trapped air in the air chamber at the upper portion of the device. The thin column of blood then pulses back and forth in the guideway in response to the patient's heartbeat. This provides a visual indication that the needle tip is in a blood vessel. However, it can sometimes be difficult for a user of the device to see movement of the blood column, and there is no provision for tactile detection of the pulsating blood pressure.
Accordingly, there is a need for an improved device which allows for convenient visual and tactile confirmation of when an associated vascular entry needle enters a selected blood vessel, but which contains the blood to prevent its escape with the attendant contamination risks.
In addition, there is a need for a blood containment device that includes a flexible membrane that can fill with blood and provide visual and/or tactile confirmation of proper needle placement, which is configured to prevent or at least minimize leakage of blood while allowing for the venting of air therefrom.
Such blood containment devices having improved capability of preventing leakage of blood are disclosed and claimed herein.